Herpetology Notes, volume 11: 227-232 (2018) (published online on 28 March 2018) Diet of Enyalius catenatus (Wied, 1821) (Reptilia: Leiosauridae) from Serra Bonita Reserve, Bahia, Brazil Débora Rocha Cruz1, Iuri Ribeiro Dias1, Tadeu Teixeira Medeiros1 and Mirco Solé1,2,* Abstract. Lizards of the genus Enyalius are restricted to forested areas distributed throughout eastern South America, but little is known about their ecology. The aim of this study was to analyse the diet of Enyalius catenatus (Wied, 1821) in the Serra Bonita Reserve. Specimens were found through active search and using pitfall traps. Individuals were measured and underwent a stomach flushing procedure to retrieve stomach contents. Prey was identified to the lowest possible taxonomical level. The most numerous items retrieved from the stomachs were: Isoptera, Hymenoptera (Formicidae) and Lepidoptera larvae. Items that showed higher relative frequencies of occurrence were, respectively, Lepidoptera larvae, Isopoda and Araneae. Volumetrically, Lepidoptera larvae, Orthoptera and Isoptera reached the highest values. The Index of Relative Importance (IRI) revealed Lepidoptera larvae as the most important food item. The diet composition revealed that lizards did not actively search for aggregated food sources and that their feeding strategy could be better described as being that of a “sit-and-wait” predator. Keywords: Foraging, lizard, Isoptera, Leiosauridae Introduction Ávila-Pires, 1995; Rodrigues et al., 2006). While the ecology of ground dwelling lizards as e g. the members The Atlantic Forest is a biome with very high reptile of the genera Ameiva, Ameivula and Tropidurus has diversity and endemism, but despite being the best been intensively studied (Fialho et al., 2000; Van Sluys studied biome in Brazil basic information about many et al., 2004a; Rocha and Siqueira, 2008; Siqueira et al., reptiles inhabiting it is still scarce (Marques and 2010; Siqueira et al., 2013; Passos et al., 2015; Santos Sazima, 2004). This is probably related to the difficulty et al. 2015), little is known about the ecology of lizards of observing them, as several reptiles remain motionless living on shrubs and trees as e.g. members of the genus most of the time and show low population densities Enyalius (Van Sluys et al., 2004b). (Passos et al., 2015). In Brazil, the Leiosauridae family Studied species of the genus Enyalius feed mainly consists out of 15 species, 10 of these belonging to the on terrestrial arthropods (Sousa and Cruz, 2008). For genus Enyalius (Costa and Bérnils, 2015). Lizards of the Enyalius catenatus, Vanzolini (1972) reported a diet genus Enyalius (Wied, 1821) are restricted to forested composed of Blattaria, larval Coleoptera, Gryllidae, areas and are distributed throughout eastern South Diplopoda, Chilopoda, Opiliones and Oligochaeta America, mainly in the Atlantic Forest (where most for 42 individuals of a population from Santa Teresa, species of this genus are endemic), but also with one Espírito Santo state, and Boraceia, Caraguatatuba and species in the Amazon (Etheridge, 1969; Jackson, 1978; São Sebastião Island in São Paulo state. However, the Index of Relative Importance (a metric proposed by Pinkas et al. (1971) only one year before Vanzolini´s work was published) and frequency of each prey was 1 Department of Biological Sciences, Universidade Estadual de not reported by this author and thus it was not possible Santa Cruz, Rodovia Ilhéus-Itabuna, Km. 16, Salobrinho, to assess how much each prey category contributed to CEP: 45662-000 Ilhéus – Bahia, Brazil. the diet. 2 Herpetology Section, Zoologisches Forschungsmuseum Alexander Koenig, Adenauerallee 160, D-53113 Bonn, Enyalius catenatus (Figure 1) is distributed in the Germany. northeastern portion of the Atlantic Forest, north of the * Corresponding author. E-mail: [email protected] Jequitinhonha River to the state of Rio Grande do Norte 228 Débora Rocha Cruz et al. Data Collection.—Data was gathered between the months of December 2009 to November 2010, during monthly fieldtrips of five days each. The specimens were found through active search and by using 100- litre pitfall traps (12 traps) (Cechin and Martins, 2000) arranged in 24 transects of 100 m each installed in the forest and in 9 transects of 50 m located near streams. After capture, individuals were transferred to the laboratory located in the reserve headquarters, where their snout-vent length (SVL) and the mouth gape was measured using a 0.1 mm precision calliper. After the measurements, to avoid death of a representative number of specimens, we used a stomach-flushing method to obtain food items (Solé et al., 2005). A 60 ml syringe was coupled to a water pipe and then introduced Figure 1. Enyalius catenatus, photographed in Serra Bonita. through the oesophagus into the stomach of the animal. The whole content of the syringe was injected and the contents expelled by the animal collected in a container (Porto et al., 2013). While it is mostly found in humid and fixed in 70% ethanol. This procedure was repeated forests it can also occur in dryer forest enclaves as e.g. until reaching the point when no more content was forced in the Chapada Diamantina (Freitas, 2011). It shows out. Then, a final flush was performed. After finishing arboreal habits and is often found at a height of 3-5 the procedure the animals were kept in quarantine meters but can also be found on the ground (Vanzolini, and released on the last day of the monthly fieldwork 1972). activity into their habitat avoiding major disruption to In this study we aimed to assess the diet of an Enyalius the specimen (Solé et al., 2005). Stomach contents were catenatus population from a forest environment and analysed and identified to the taxonomic level of Order thus gain insights into the diet of this arboreal lizard. with the aid of a stereomicroscope. Data Analysis.—In order to calculate the volume of each Material and Methods prey, we measured the length and width of undigested Study Area.—The study was conducted at Serra Bonita items. Partially digested prey had their original sizes Reserve, located in the municipalities of Camacan estimated from fragments using the regression formulas and Pau-Brasil, in the state of Bahia, Brazil (15°23’S; proposed by Hirai and Matsui (2001). The volume 39°33’W). The reserve has altitudinal gradients was measured with the following formula for ellipsoid varying between 200 and 950 meters above sea level. bodies proposed by Dunham (1983): Its vegetation consists of Dense Forests Rainforests with elements of Semideciduous Seasonal Forests in V = 4/3π (L/2) (W/2)2 the lower areas and Moist Submontane Forests in the Where V = volume, L = length and W = width of prey. higher areas of the mountain. The reserve has about The Index of Relative Importance (IRI) was calculated 50% of primary forests, while the remaining areas are to reduce bias that may exist in the description of animal composed of mosaics that include secondary forests, diets, using the formula below proposed by Pinkas et pastures and so called cabrucas, cocoa plantations that al. (1971): keep some of the original old grown trees for shading (Instituto Uiraçu, 2014). IRIt = (POt)(PIt + PVt) The average monthly rainfall was 160.9 mm (23.2 – 270.8 mm) and the mean minimum air temperature was Where POt is the percentage of occurrence (100 x 17.2 ºC (13.5 – 20.1 ºC) and maximum 25.8 ºC (21.9 – number of stomachs containing item t / total number of 29.4 ºC) (Dias et al., 2014). The climate is characterized stomachs), PIt is the percentage of items (100 x total as hot and humid, without a dry season, corresponding number t of individuals in all stomachs / total number to the Af type (tropical rainforest climate) of Köppen of individuals of all categories in all stomachs) and PVt (1936). is the percentage of the volume (total volume x 100 t in Diet of Enyalius catenatus from Serra Bonita Reserve, Bahia, Brazil 229 Table 1. Analysed stomach contents of Enyalius catenatus. N is the number of items in all stomachs, N% is the relative number of each item in all the stomachs, F is the number of stomachs in which the item was found, F% is the relative number of occurrences 1 Table 1: Analyzed stomach contents of Enyalius catenatus. N is the number of items in all stomachs, N% is the of each item in2 all stomachs,relative number V ofis eachthe itemtotal in volume all the stomachs, of each F isitem the number in all ofstomachs, stomachs in V% which is the the item relative was found, number F% per item and IRI is the Index of Relative3 Importanceis the relative number of Pinkas. of occurrences The three of each categories item in all stomachs,with the V highest is the total IRI volume values of each are item highlighted in all in bold. The acronyms 4 stomachs, V% is the relative number per item and IRI is the Index of Relative Importance of Pinkas. The Im and Lv refer5 to acronymsimago and Im and larva Lv referrespectively. to imago and larva respectively. 6 7 Taxon N N% V V% F F% IRI Insecta Hemiptera 4 0.7 183.6 0.2 4 12.5 11.4 Hymenoptera Vespidae 1 0.2 21.7 >0.1 1 3.1 0.6 Hymenoptera Formicidae 28 4.8 3345.7 4.2 3 9.4 84 Hymenoptera other 2 0.3 197.2 0.3 2 6.2 3.7 Diptera 2 0.3 67.6 0.1 2 6.2 2.7 Orthoptera 13 2.2 14863 18.5 10 31.3 646.9 Coleoptera 12 2.1 6023 7.5 9 28.1 268.3 Lepidoptera (Im) 1 0.2 119.6 0.2 1 3.1 1 Lepidoptera (Lv) 21 3.6 37893.7 47.1 14 43.8 2217.9 Blattaria 1 0.2 18.9 >0.1 1 3.1 0.6 Dermaptera 1 0.2 421 0.5 1 3.1 2.2 Isoptera 445 76.2 7831.7 9.7 3 9.4 805.6 Myriapoda Diplopoda 4 0.7 2477.1 3.1 3 9.4 35.3 Chilopoda 1 0.2 100.3 0.1 1 3.1 0.9 Crustacea Isopoda 16 2.7 520 0.7 12 37.5 127 Arachnida Araneae 12 2.1 3651.5 4.5 11 34.4 226.7 Acarina 20 3.4 5.1 >0.1 1 3.1 10.7 Mollusca Gastropoda 5 0.9 2713 3.4 2 6.3 26.4 Total 584 80454.6 8 9 all individuals stomachs / total volume of all categories larvae (N=21, N%=3.7).